Composition for forming an ink layer, and laminate

Abstract

The present invention provides a laminate obtained by laminating an ink layer, such as a design printing layer, onto a polyolefin film, which exhibits excellent adhesion between the polyolefin film and the ink layer without the need for an anchor coat layer, and an ink layer forming composition for forming the ink layer constituting the laminate. [Solution] An ink layer forming composition for direct coating of a polyolefin film, comprising a binder resin, a colorant, and a solvent, wherein the binder resin mainly contains a chlorinated polyolefin resin among the binder resin components.

Description

Technical Field

[0001] The present invention relates to a composition for forming an ink layer and a laminate in which a polyolefin film and an ink layer are laminated adjacent to each other.

Background Art

[0002] An overlap film is a type of packaging material that covers an adherend and is used by being attached to various adherends such as containers containing food and daily necessities by heat shrinkage. For example, many cup containers containing instant noodles are covered and packaged with an overlap film provided with an ink layer such as a design printing layer for patterns, trademarks, product instructions, etc. By the way, an overlap film using a polyolefin film such as a heat-shrinkable polyolefin-based film is known. When a polyolefin-based film is subjected to corona discharge treatment, during post-processing, for example, when the film is sealed and packaged with a fusion heater, the sealed part peels off due to the influence of the corona discharge treatment, and there is a problem that packaging cannot be done properly. Therefore, it is necessary to print without performing corona discharge treatment. However, when corona discharge treatment is not performed, the adhesion between the polyolefin-based film and an ink layer such as a design printing layer is poor. Therefore, it is necessary to take measures to improve the adhesion between the polyolefin-based film and an ink layer such as a design printing layer. Therefore, an anchor coat layer is provided between the heat-shrinkable polyolefin-based film and the design printing layer. For example, an overlap film having a heat-shrinkable polyolefin-based film, an anchor coat layer laminated adjacent to the heat-shrinkable polyolefin-based film, and a design printing layer laminated adjacent to the anchor coat layer has been proposed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0004] While Patent Document 1 described above includes an anchor coat layer as an essential component, a configuration that does not require an anchor coat layer is preferable from the viewpoint of reducing the amount of materials used and simplifying the process. Therefore, even in laminates where an anchor coat layer is not provided and the polyolefin film and the ink layer, such as the design printing layer, are formed adjacent to each other, there is a need to provide a laminate with excellent adhesion between the polyolefin film and the ink layer, such as the design printing layer. Therefore, the present invention aims to provide a laminate obtained by laminating an ink layer, such as a design printing layer, onto a heat-shrinkable polyolefin film, or any polyolefin film regardless of whether it is heat-shrinkable, and which exhibits excellent adhesion between the polyolefin film and the ink layer without the need for an anchor coat layer, and an ink layer forming composition for forming the ink layer constituting the laminate. Furthermore, an objective is to provide an ink layer-forming composition for forming an ink layer adjacent to a polyolefin film that not only exhibits excellent adhesion but also has excellent printability when ink is applied in multiple layers (also known as ink overprinting). [Means for solving the problem]

[0005] As a result of diligent research to solve the above-mentioned problems, the inventors of the present invention have found that an ink layer-forming composition containing a chlorinated polyolefin resin as the main component as a binder resin can solve the above-mentioned problems of the present invention, and have completed the present invention.

[0006] In other words, the present invention encompasses the following embodiments. [1] An ink layer forming composition for direct coating of polyolefin film, It contains a binder resin, a colorant, and a solvent. The aforementioned binder resin is an ink layer forming composition that contains a chlorinated polyolefin resin as the main component among the binder resin components. [2] The ink layer forming composition according to [1], wherein the binder resin further contains at least one of the following resins: nitrated cotton resin, polyamide resin, ketone formaldehyde resin, and acrylic resin. [3] The ink layer forming composition according to [1] or [2], wherein the solvent is an organic solvent containing at least one of an aliphatic hydrocarbon solvent, an ester solvent, an alcohol solvent, and a glycol ether solvent, when the ink layer forming composition is an oil-based ink composition. [4] The ink layer forming composition according to [1] or [2], wherein the solvent is water, when the ink layer forming composition is an aqueous ink composition. [5] The ink layer forming composition according to any one of [1] to [4], further comprising wax and silica. [6] A laminate comprising a polyolefin film and an ink layer laminated adjacent to each other, A laminate in which the ink layer is a layer formed using an ink layer forming composition described in any of [1] to [5]. [7] The laminate according to [6], wherein the polyolefin film is a heat-shrinkable film. [Effects of the Invention]

[0007] The present invention provides a laminate obtained by laminating an ink layer, such as a design printing layer, onto a polyolefin film, which exhibits excellent adhesion between the polyolefin film and the ink layer without the need for an anchor coat layer, and an ink layer forming composition for forming the ink layer constituting the laminate. Furthermore, the present invention provides an ink layer forming composition for forming an ink layer on a polyolefin film that not only exhibits excellent adhesion but also has excellent printability when ink is applied in multiple layers (also known as ink overprinting). [Modes for carrying out the invention]

[0008] The present invention will be described in detail below. The following description of the constituent elements is illustrative for illustrating the present invention, and the present invention is not limited to these elements.

[0009] (Ink layer forming composition) The present invention provides an ink layer-forming composition for direct coating onto a polyolefin film. The present invention provides an ink layer-forming composition for forming an ink layer in a laminate in which a polyolefin film and an ink layer are laminated adjacent to each other. A detailed explanation of "laminated structures" (for example, overlap films) formed by laminating polyolefin films and ink layers adjacent to each other will be provided later. The ink layer-forming composition of the present invention contains a binder resin, a colorant, and a solvent. The ink layer-forming composition of the present invention may contain various additives as needed, in addition to a binder resin, colorant, and solvent. The binder resin contains chlorinated polyolefin resin as its main component. The binder resin may further contain at least one of the following resins: nitrated cotton resin, polyamide resin, ketone formaldehyde resin, and acrylic resin. Here, "containing chlorinated polyolefin resin as the main component" among the binder resin components means that chlorinated polyolefin resin accounts for the largest proportion of the resin components that make up the binder resin compared to other resins. For example, if the only resin component constituting the binder resin is chlorinated polyolefin resin, then chlorinated polyolefin resin makes up 100% of the binder resin, and therefore it can be said that it contains chlorinated polyolefin resin as the main component. Also, as shown in the preparation example of oily color 2 in the examples described later, for example, if the binder resin contains nitrated cotton resin, polyamide resin, and ketone formaldehyde resin in addition to chlorinated polyolefin resin, the chlorinated polyolefin resin is a 60% solution, so the proportion is 8.3 × 0.6 = 4.98 parts by mass, while the proportion of nitrated cotton resin is 4.0 parts by mass, the proportion of polyamide resin is 3.1 parts by mass, and the proportion of ketone formaldehyde resin is 1.2 parts by mass. Therefore, among the resin components constituting the binder resin, the proportion of chlorinated polyolefin resin is the largest compared to the other resins, and in this preparation example, chlorinated polyolefin resin is contained as the main component. In the present invention, by incorporating a chlorinated polyolefin resin as the main component in the binder resin of the ink layer forming composition, it is possible to produce a laminate that has adhesion as a laminated film and improved printability in the areas where ink is applied in layers, as shown in the examples below.

[0010] <Binder resin> As described above, the binder resin according to the present invention contains a chlorinated polyolefin resin as its main component. The binder resin according to the present invention may consist solely of a chlorinated polyolefin resin, or it may be composed of resins other than chlorinated polyolefin resins. The ink layer-forming composition may be an oil-based ink composition or an aqueous ink composition, and a suitable binder resin can be selected as appropriate, taking into consideration whether the ink composition is oil-based or aqueous. For example, in addition to chlorinated polyolefin resin, the binder resin may contain at least one of the following resins: nitrated cotton resin, polyamide resin, ketone formaldehyde resin, and acrylic resin. As a more preferred embodiment of the binder resin, for example, when the composition for forming an ink layer is an oil-based ink composition, examples of the binder resin other than the chlorinated polyolefin resin include nitrocellulose resin, polyamide resin, or ketone formaldehyde resin. Further, as a more preferred embodiment of the binder resin, for example, when the composition for forming an ink layer is an aqueous ink composition, an acrylic resin can be mentioned. The binder resin (binder resin solution) is preferably contained in the composition for forming an ink layer at 8.0 to 70.0% by mass, and more preferably at 10.0 to 65.0% by mass.

[0011] <<Chlorinated Polyolefin Resin>> The composition for forming an ink layer contains a chlorinated polyolefin resin as a main component as a binder resin component. The chlorinated polyolefin resin according to the present invention is not particularly limited as long as it is a polyolefin resin in which at least a part of hydrogen atoms is substituted by chlorine atoms. Examples of the chlorinated polyolefin resin include chlorinated polyethylene, chlorinated polypropylene, acrylic-modified or urethane-modified chlorinated polyolefin-based resins obtained by modifying chlorinated polyethylene or chlorinated polypropylene with an acrylic polymer or urethane polymer having an ethylenically unsaturated bond. The weight average molecular weight of the chlorinated polyolefin resin is preferably 5,000 to 300,000, more preferably 40,000 to 220,000, and even more preferably 50,000 to 150,000. In addition, in order to improve the adhesion of the chlorinated polyolefin resin to the substrate of the polyolefin film, the chlorine content is preferably 15 to 45% by mass. Further, from the viewpoint of solubility in an organic solvent, the chlorine content is more preferably 26 to 43% by mass. Here, the chlorine content means the mass percentage of chlorine atoms in 100% by mass of the chlorinated polyolefin resin. The chlorinated polyolefin resin is preferably contained in the ink layer-forming composition in an amount of 10.0 to 29.0% by mass, and more preferably in an amount of 10.0 to 25.0% by mass, by solid content. The chlorinated polyolefin resin is preferably contained in the ink layer-forming composition in an amount of 25.1 to 100.0% by mass, and more preferably in an amount of 33.4 to 80.0% by mass, by solid content, of 100% by mass of the binder resin.

[0012] As described above, the binder resin according to the present invention may further contain at least one of the following resins: nitrated cotton resin, polyamide resin, ketone formaldehyde resin, and acrylic resin.

[0013] <<Nitrified cotton resin>> The molecular weight of the nitrated cotton resin (nitrocellulose resin) is preferably 5,000 to 200,000, and more preferably 10,000 to 50,000. Furthermore, a glass transition temperature of 120°C to 180°C is preferred. The nitrated cotton resin (nitrocellulose resin) is preferably obtained as a nitrate ester by reacting natural cellulose with nitric acid, in which three hydroxyl groups in the six-membered ring of the anhydrous glucopyranose group in the natural cellulose are replaced with nitrate groups.

[0014] <<Polyamide resin>> The polyamide resin is, for example, a thermoplastic polyamide soluble in organic solvents that can be obtained by polycondensation of a polybasic acid and a polyhydric amine. In particular, it is preferable that the polyamide resin contains a reaction product of an acid component containing polymerized fatty acids and / or dimer acids and an aliphatic and / or aromatic polyamine, and more preferably that it partially contains primary and secondary monoamines. The polybasic acids used as raw materials for polyamide resins are not limited to the following, but include adipic acid, sebacic acid, azelaic acid, phthalic anhydride, isophthalic acid, suberic acid, glutaric acid, fumaric acid, pimelic acid, oxalic acid, malonic acid, succinic acid, maleic acid, terephthalic acid, 1,4-cyclohexyldicarboxylic acid, trimellitic acid, dimeric acid, hydrogenated dimeric acid, and polymerized fatty acids. Among these, polyamide resins containing structures derived from dimeric acid or polymerized fatty acids as the main component (50% by mass or more in the polyamide resin) are preferred. Here, polymerized fatty acids are obtained by cyclization reactions of unsaturated fatty acids, and include monobasic fatty acids, dimerized polymerized fatty acids (dimeric acid), and trimerized polymerized fatty acids. The fatty acids constituting dimeric acid or polymerized fatty acids can preferably be derived from natural oils such as soybean oil, palm oil, and rice bran oil, and those obtained from oleic acid and linoleic acid are preferred. Monocarboxylic acids can also be used in combination with polybasic acids. Examples of monocarboxylic acids that can be used in combination include acetic acid, propionic acid, lauric acid, palmitic acid, benzoic acid, and cyclohexanecarboxylic acid. Examples of polyhydric amines include polyamines and primary or secondary monoamines. Examples of polyamines used in polyamide resins include aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, and methylaminopropylamine, and aliphatic polyamines such as diethylenetriamine and triethylenetetramine. Examples of alicyclic polyamines include cyclohexylenediamine and isophoronediamine. Examples of aromatic aliphatic polyamines include xylylenediamine, and examples of aromatic polyamines include phenylenediamine and diaminodiphenylmethane. Furthermore, examples of primary and secondary monoamines include n-butylamine, octylamine, diethylamine, monoethanolamine, monopropanolamine, diethanolamine, and dipropanolamine.

[0015] <<Ketoneformaldehyde resin>> Examples of ketone formaldehyde resins include condensates of methyl ethyl ketone, methyl isobutyl ketone, acetophenone, cyclohexanone and / or methylcyclohexanone with formaldehyde.

[0016] <<Acrylic resin>> There are no particular restrictions on the acrylic resin, and examples include homopolymers or copolymers of (meth)acrylate, and copolymers obtained by copolymerizing (meth)acrylate with vinyl monomers that can copolymerize with it. Examples of vinyl monomers that can copolymerize with (meth)acrylates include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, isopropyl (meth)acrylate, and isobutyl (meth)acrylate; aromatic (meth)acrylates such as benzyl (meth)acrylate; hydroxyl group-containing monomers such as 2-hydrodoxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; alkyl polyalkylene glycol mono(meth)acrylates such as methoxypolyethylene glycol mono(meth)acrylate and methoxypolypropylene glycol mono(meth)acrylate; fluorinated (meth)acrylates such as perfluoroalkylethyl (meth)acrylate; aromatic vinyl compounds such as vinylnaphthalene, vinylanthracene, and 1,1-diphenylethylene; glycidyl (meth)acrylate, epoxy (meth)acrylate, ethylene glycol di(meth)acrylate, and diethylene glycol Licol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylene glycol tetra(meth)acrylate, 2-hydroxy-1,3-diacroxypropane, 2,2-bis[4-(acryloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloxyethoxy)phenyl]propane, dicyclopentenyl(meth)acrylate, tricyclodecanyl(meth)acrylate, tris(acryloxyethyl)isocyanurate, urethane(meth)acrylate, etc. Examples of methylamine compounds include alkylamino group-containing (meth)acrylates such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and dimethylaminopropyl (meth)acrylate; vinylpyridine compounds such as 2-vinylpyridine, 4-vinylpyridine, and naphthylvinylpyridine; and conjugated dienes such as 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and 1,3-cyclohexadiene. These monomers can be used individually or in combination of two or more. The above copolymer can be produced, for example, by polymerizing various monomers in the temperature range of 50°C to 180°C in the presence of a polymerization initiator, with a temperature range of 80°C to 150°C being more preferable. Examples of polymerization methods include bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Examples of polymerization modes include random copolymers, block copolymers, and graft copolymers. The weight-average molecular weight of the acrylic resin is preferably in the range of 5,000 to 200,000, and more preferably in the range of 10,000 to 100,000.

[0017] <Coloring agent> Conventional known pigments or dyes can be used as colorants. Examples of inorganic pigments include colored pigments such as titanium dioxide, zinc oxide, aluminum oxide, red iron oxide, antimony red, cadmium yellow, cobalt blue, Prussian blue, ultramarine, carbon black, and graphite; extender pigments such as silica, calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, and talc; and pearl pigments such as mica and metal oxide-coated mica. Inorganic pigments can be used individually or in combination of two or more. Among these, it is preferable that the inorganic pigment contains at least one selected from metal oxides such as titanium dioxide, zinc oxide, and aluminum oxide, silica, calcium carbonate, and mica, and it is more preferable that it contains titanium dioxide.

[0018] As colorants contained in the design printing layer described later, pigments are preferred, and examples include inorganic pigments and organic pigments used in general inks, paints, and recording materials. Examples of organic pigments include soluble azo, insoluble azo, azo, phthalocyanine, halogenated phthalocyanine, anthraquinone, anthancerone, dianthaquinonyl, anthrapyrimidine, perylene, perinone, quinacridone, thioindigo, dioxazine, isoindolinone, quinophthalone, azomethine azo, flavanthrone, diketopyrrolopyrrole, isoindoline, indanthrone, and carbon black. Other examples include carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, chromophthal yellow, chromophthal red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigobordeaux, thioindigomagenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, and daylight fluorescent pigments. Both unacidified and acidified pigments can be used.

[0019] <Solvent> The solvent contained in the ink layer-forming composition of the present invention may be an organic solvent or an aqueous solvent containing water. If the ink layer-forming composition is an oil-based ink composition, the solvent is preferably an organic solvent containing at least one of the following: an aliphatic hydrocarbon solvent, an ester solvent, an alcohol solvent, and a glycol ether solvent. Furthermore, if the ink layer-forming composition is an aqueous ink composition, the solvent should preferably be an aqueous solvent containing water.

[0020] <<Organic Solvents>> As described above, the organic solvent according to the present invention preferably contains at least one of the following: aliphatic hydrocarbon solvents, ester solvents, alcohol solvents, and glycol ether solvents. Solvents can be used individually or in combination of two or more. For example, by using alcohol-based solvents in addition to ester-based solvents, it is possible to suppress the deterioration of flexographic printing plates during flexographic printing. Examples of organic solvents according to the present invention include aliphatic hydrocarbon organic solvents such as hexane, methylcyclohexane, heptane, octane, and decane; ester solvents such as methyl acetate, ethyl acetate, isopropyl acetate, n-propyl acetate, butyl acetate, amyl acetate, ethyl formate, and butyl propionate; alcohol solvents such as methanol, ethanol, propanol, butanol, and isopropyl alcohol; and glycol ether solvents such as ethylene glycol (mono,di)methyl ether, ethylene glycol (mono,di)ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono,di)methyl ether, diethylene glycol (mono,di)ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono,di)methyl ether, propylene glycol (mono,di)methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono,di)methyl ether.

[0021] The organic solvent is preferably contained in the ink layer-forming composition in an amount of 40.0 to 90.0% by mass, and more preferably in an amount of 60.0 to 80.0% by mass.

[0022] <<Water-based solvent>> Examples of aqueous solvents according to the present invention include water, and mixed solvents obtained by mixing a water-soluble solvent that is miscible with water with water. Examples of water-soluble solvents include alcohol solvents such as methanol, ethanol, n-propanol, and isopropanol; ketone solvents such as acetone and methyl ethyl ketone; polyalkylene glycols such as ethylene glycol, diethylene glycol, and propylene glycol; alkyl ethers of polyalkylene glycols; and lactam solvents such as N-methyl-2-pyrrolidone. In this invention, water alone may be used, or a mixture of water and a water-soluble solvent that is miscible with water may be used; however, from the viewpoint of safety and environmental impact, water alone is more preferable.

[0023] Specific examples of water include natural water, purified water, distilled water, ion-exchanged water, pure water, and ultrapure water (e.g., Milli-Q water).

[0024] As described above, the ink layer-forming composition of the present invention may contain various additives, for example, at least one of wax and silica.

[0025] <wax> The ink layer-forming composition may contain wax. For example, polyolefin waxes or fatty acid amide waxes are preferable as the wax. Examples of polyolefin waxes include oxidized polyethylene wax and oxidized polypropylene wax. Examples of fatty acid amide waxes include saturated fatty acid amides such as stearic acid amide and palmitic acid amide, and unsaturated fatty acid amides such as erucic acid amide, substituted amides, and aromatic amides.

[0026] The ink layer-forming composition of the present invention can be applied, for example, to a polyolefin film substrate, and the coating film can be dried to form an ink layer adjacent to the polyolefin film. The thickness of the ink layer is not particularly limited, but is preferably, for example, 0.1 μm to 5 μm.

[0027] (Laminated structure) The laminate of the present invention has an ink layer formed using the ink layer forming composition of the present invention. The laminate of the present invention is formed by laminating a polyolefin film and an ink layer adjacent to each other.

[0028] <Layer structure of the laminate> As described above, the laminate of the present invention has polyolefin film / ink layers laminated adjacent to each other. By using the ink layer-forming composition of the present invention, the adhesion between the ink layer and the polyolefin film substrate is good, and the ink transfer properties on the polyolefin film in the areas where the ink is applied in multiple layers are improved. Furthermore, by using the ink layer-forming composition of the present invention, the scratch resistance and abrasion resistance of the ink layer surface when the ink is applied in multiple layers are good. A more preferred embodiment of the laminate of the present invention is, for example, a laminate in which a polyolefin film, a design printing layer, and a white printing layer of a second printing layer are laminated in this order. For example, the design printing layer is provided in direct contact with the back surface of the polyolefin film, and the second printing layer (white printing layer) is provided in direct contact with the back surface of the design printing layer.

[0029] <Polyolefin film> As the polyolefin film, a film made of a thermoplastic resin mainly composed of olefin resin can be used. Specific examples of olefin resins include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; polypropylene; ethylene-propylene copolymers; α-olefin polymers; ethylene-vinyl acetate copolymers; ethylene-vinyl alcohol copolymers; ethylene-acrylic acid copolymers; ethylene-methyl methacrylate copolymers; ethylene-ethyl acrylate copolymers; cyclic olefin resins; ionomer resins; and polymethylpentene. Modified olefin resins are obtained by modifying olefin resins with acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, and other unsaturated carboxylic acids. Preferred polyolefin resins include polyethylene such as biaxially oriented polypropylene (OPP), unoriented polypropylene (CPP), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE); acid-modified polyethylene; acid-modified polypropylene; and copolymerized polypropylene.

[0030] Furthermore, it is also preferable to use a polyolefin film made from a material containing biomass-derived components. Biomass films are sold by various companies, and for example, sheets listed in the biomass certified product list provided by the Japan Organic Resources Association can be used.

[0031] A well-known example of a film made from biomass-derived ethylene glycol is derived from ethanol produced from biomass (biomass ethanol). For example, biomass-derived ethylene glycol can be obtained by conventionally known methods, such as a method that produces ethylene glycol via ethylene oxide from biomass ethanol. Alternatively, commercially available biomass ethylene glycol may be used; for example, the biomass ethylene glycol commercially available from India Glycol can be suitably used.

[0032] Alternatively, products using biomass raw materials, distinguished by their biomass plasticity as defined by ISO 16620 or ASTM D6866, are also available. Radioactive carbon is present in the atmosphere at a rate of 1 in 10¹² particles. 14 Since carbon is present and this ratio does not change even with atmospheric carbon dioxide, this ratio does not change even in plants that fix this carbon dioxide through photosynthesis. For this reason, the carbon in plant-derived resins is radioactive carbon. 14 It contains C. In contrast, the carbon in fossil fuel-derived resins is radioactive carbon. 14 It contains almost no carbon. Therefore, the radioactive carbon in the resin is measured using an accelerator mass spectrometer. 14 By measuring the concentration of C, the proportion of plant-derived resin in the resin, i.e., the biomass plasticity, can be determined. Examples of plant-derived low-density polyethylene that are biomass plastics with a biomass plasticity of 80% or more, preferably 90% or more, as defined by ISO 16620 or ASTM D6866, include Braskem's product names "SBC818," "SPB608," "SBF0323HC," "STN7006," "SEB853," and "SPB681," and films made using these as raw materials can be suitably used.

[0033] For example, as an alternative to conventional polyolefin films using petroleum-based raw materials, biomass polyolefin films such as biomass polyethylene films and biomass polyethylene-polypropylene films, which contain polyethylene resin made from biomass-derived ethylene glycol, are also known. The polyethylene resin is not particularly limited except for the use of biomass-derived ethylene glycol as part of the raw materials. Examples include ethylene homopolymers and copolymers of ethylene and α-olefins with ethylene as the main component (ethylene-α-olefin copolymers containing 90% by mass or more of ethylene units). These can be used individually or in combination of two or more types. The α-olefin constituting the copolymer of ethylene and α-olefin is not particularly limited, and examples include α-olefins having 4 to 8 carbon atoms, such as 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. Known polyethylene resins such as low-density polyethylene resin, medium-density polyethylene resin, and linear low-density polyethylene resin can be used. Among these, linear low-density polyethylene resin (LLDPE) (a copolymer of ethylene and 1-hexene, or a copolymer of ethylene and 1-octene) is preferred from the viewpoint of making it even less likely for damage such as punctures or tears to occur when the films rub against each other, with a density of 0.910 to 0.925 g / cm³. 3 A linear low-density polyethylene resin is more preferable.

[0034] The biomass film may be a laminate formed by stacking multiple biomass films, or it may be a laminate formed by combining a conventional petroleum-based film with a biomass film.

[0035] The base material for the polyolefin film can be manufactured using conventionally known film-forming methods such as extrusion, casting, T-die, cutting, and inflation, using the resin described above. It may be an unstretched film, or, from the viewpoint of strength, dimensional stability, and heat resistance of the polyolefin film, it may be stretched in one or two axes using a tenter method, tubular method, or the like.

[0036] Polyolefin films may contain additives as needed. Specifically, plastic compounding agents and additives such as elastomers, lubricants, crosslinking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, and pigments may be added to improve or modify properties such as processability, heat resistance, weather resistance, mechanical properties, dimensional stability, oxidation resistance, slipperiness, release properties, flame retardancy, mold resistance, electrical properties, and strength. The amount of additives added should be adjusted to a level that does not affect other performance characteristics or recyclability. For example, by using a polyolefin containing titanium dioxide, it may be used as a milky white colored film.

[0037] The film thickness of the polyolefin film substrate is not particularly limited and can be appropriately selected within the range of 0.1 to 300 μm from the viewpoint of moldability and transparency. Preferably, it is in the range of 0.3 to 100 μm. If it is less than 0.1 μm, the strength will be insufficient, and if it exceeds 300 μm, the rigidity will be too high, which may make processing difficult.

[0038] The polyolefin film can be either a heat-shrinkable polyolefin film or a non-heat-shrinkable polyolefin film; either type should be selected appropriately considering the application method and usage form of the polyolefin film.

[0039] <<Heat-shrinkable polyolefin film>> Thermal shrinkability refers to the property of shrinking when heated to a required temperature (for example, 70°C to 160°C). A thermal shrinkable polyolefin film shrinks in at least one direction (first direction) within its plane, and preferably in two orthogonal directions (first and second directions) within its plane.

[0040] A heat-shrinkable polyolefin film is a colorless or colored transparent heat-shrinkable film in which the main component resin of the film is a polyolefin-based resin. The heat-shrinkable polyolefin film is not particularly limited, and examples include a polypropylene film made of polypropylene; a polyethylene film made of polyethylene; and a polypropylene film is preferred. Examples of polypropylene include propylene homopolymers and propylene-ethylene copolymers, while examples of polyethylene include polyethylene homopolymers and polyethylene copolymers. The thickness of the heat-shrinkable polyolefin film is not particularly limited, but is preferably 10 μm to 60 μm, and more preferably 12 μm to 40 μm.

[0041] <Ink layer> The ink layer according to the present invention may be an ink layer formed using the above-described oil-based ink composition, so-called organic solvent ink (an ink using an organic solvent, also referred to herein as an oil-based ink), or an ink layer formed using the above-described aqueous ink composition, so-called water-based solvent ink containing water (an ink using a water-based solvent, also referred to herein as an aqueous ink). Furthermore, the ink layer according to the present invention may be a single layer or formed from two or more layers. For example, the ink layer may consist of two or more ink layers, each having a design printing layer on which various design displays such as a product name, image, ingredient list, barcode, 2D code, and warning label are displayed, and a second printing layer that is colorless transparent, colored transparent, unpatterned single color, or unpatterned multi-color. Furthermore, the design printing layer and the second printing layer may be composed of multiple layers.

[0042] As mentioned above, the design printing layer is a printed layer on which various design elements such as product name, image, ingredient list, barcode, 2D code, and warnings are displayed. The design printing layer contains a binder resin and a coloring agent. Conventional known pigments or dyes can be used as colorants.

[0043] As described above, the second printing layer is a colorless transparent, colored transparent, unpatterned single-color, or unpatterned multi-color printing layer. The second printing layer contains a binder resin and an inorganic pigment. The inorganic pigments are as described in the <Colorants> section of the above (Ink Layer Forming Composition).

[0044] As colorants to be contained in the design printing layer, pigments are preferred, for example, and examples include inorganic pigments and organic pigments that are commonly used in inks, paints, and recording materials. As for organic pigments, they are as described in the <Colorants> section of the above (Ink Layer Forming Composition).

[0045] Whether it is the design printing layer or the second printing layer, the ink (also called the ink composition) that forms the printing layer consists of the aforementioned colorants such as pigments, a binder resin, a solvent, and various other additives as needed. When the ink is an oil-based ink (organic solvent ink), in addition to chlorinated polyolefin resin, other preferred binder resins used in the oil-based ink include, for example, nitrated cotton resin, polyamide resin, and ketone formaldehyde resin, as mentioned above. If the ink is an oil-based ink, examples of solvents contained in the oil-based ink include the organic solvents mentioned above.

[0046] When the ink is a water-based ink, the binder resin contained in the water-based ink can be a water-dispersible or water-soluble resin. In addition to chlorinated polyolefin resins, for example, acrylic resins are preferably used, as mentioned above. There are no particular restrictions on the acrylic resin, and as mentioned above, examples include homopolymers or copolymers of (meth)acrylate, and copolymers obtained by copolymerizing (meth)acrylate with vinyl monomers that can copolymerize with it. Furthermore, it is preferable that the copolymer has an acid value in order to impart water dispersibility and water solubility. If the ink is a water-based ink, examples of the solvent (water-based solvent) contained in the water-based ink include water and a mixture of organic solvents that are miscible with water. Examples of organic solvents that are miscible with water include those listed in the <solvent> section of the above (ink layer forming composition).

[0047] As described above, the ink layer-forming composition may contain various additives, for example, at least one of wax and silica. Here, the wax contained in the ink layer forming composition is as described in the <wax> section of the above (ink layer forming composition).

[0048] The design print layer can be formed by printing an ink containing a binder resin and a colorant using a known printing method. The second printed layer can be formed by printing an ink containing a binder resin and an inorganic pigment using a known printing method. For example, known printing methods include printing with liquid printing inks such as gravure inks and flexographic inks. The thickness of the design printing layer is not particularly limited, but is preferably, for example, 0.1 μm to 5 μm, and the thickness of the second printing layer is not particularly limited, but is preferably, for example, 0.5 μm to 5 μm.

[0049] When methylcyclohexane is used as a solvent in an ink layer-forming composition, for example, attempting to perform flexographic printing using the composition may degrade flexible printing plates made of rubber or resin, and in some cases, it may be necessary to use special printing plates. Therefore, it is desirable to avoid including methylcyclohexane as a solvent whenever possible. In particular, it is preferable that the ink layer forming composition for forming the design printing layer does not contain methylcyclohexane as a solvent.

[0050] Furthermore, when the ink layer according to the present invention has a two-layer structure having a design printing layer and a second printing layer, it is preferable that the binder resin in both the ink layer forming composition for forming the design printing layer and the ink layer forming composition for forming the second printing layer contains chlorinated polyolefin resin as a main component. However, in order to ensure good adhesion between the polyolefin film and the ink layer, which is the objective of this invention, it is preferable that the design printing layer adjacent to the polyolefin film contains at least chlorinated polyolefin resin. The binder resin of the ink layer forming composition that forms the design printing layer contains chlorinated polyolefin resin as its main component, and the binder resin of the ink layer forming composition that forms the second printing layer also contains chlorinated polyolefin resin as its main component. As a result, not only is the adhesion between the ink layer and the polyolefin film good, but the ink transferability on the polyolefin film in areas where ink is applied in multiple layers is improved, and furthermore, the scratch resistance and abrasion resistance of the ink layer surface when ink is applied in multiple layers can be improved.

[0051] <<Preferred embodiment of the ink layer>> Preferred embodiments of the laminate including the ink layer include, for example, the embodiments described in (i) and (ii) below. (i) Polyolefin film / Solvent (oil-based) ink layer (ii) Polyolefin film / water-based ink layer Furthermore, considering that the use of water-based solvents is required for environmental reasons, the embodiment described in (ii) above is preferred. As a method for manufacturing water-based inks, for example, a mixture of pigment, water alone, or an organic solvent miscible with water (if such an organic solvent is present), a pigment dispersant, an antifoaming agent, etc., is dispersed in a disperser to obtain a pigment dispersion. A binder resin, water, an organic solvent miscible with water (if such an organic solvent is present), and additives such as a leveling agent as needed are added to the obtained pigment dispersion, and the mixture is stirred and mixed to obtain an ink composition. Dispersers commonly used in the manufacture of gravure and flexographic printing inks include bead mills, Eiger mills, sand mills, gamma mills, attritors, etc.

[0052] <Method for manufacturing laminates> The laminate according to the present invention can be manufactured, for example, as follows. An ink layer-forming composition is applied to a polyolefin film substrate, and the coated film is dried to form an ink layer. Furthermore, by changing the type of ink, multiple ink layers (printing layers) can be formed sequentially, from the first ink layer (first printing layer) to the second ink layer (second printing layer), and then, as appropriate, the third ink layer (third printing layer), the fourth ink layer (fourth printing layer), and so on.

[0053] <Applications of laminates> The laminate of the present invention can be used, for example, as an overlap film for overlap packaging, particularly for instant noodle packaging. The overlap film according to the present invention is used by heat shrinking and attaching it to various adherends. Overlap film is used as a protective film by covering the perimeter of a single adherend, or as a protective and binding film by covering the perimeter of an assembly of multiple adherends. The object to be adhered to is not particularly limited and may be a container in which an article is stored, or the article itself. Examples of objects to be coated include containers that hold instant foods such as instant noodles, dairy products such as yogurt, condiments such as jelly and pudding, beverages, seasonings, sanitary products such as shampoo, and fresh foods such as meat; as well as items themselves, such as dry cell batteries. When the object to be attached is a container containing an article, the external shape of the container is not particularly limited and may include cylindrical shapes such as cylindrical, elliptical, or square cylindrical shapes; inverted frustoconical shapes such as inverted frustoconical, inverted elliptical, or inverted square frustoconical shapes; or irregular shapes such as gourd shapes. The material of the container is not particularly limited and can include, for example, synthetic resin, foamed synthetic resin, metal, glass, ceramics, and wood.

[0054] <<Specific uses of overlapping film>> A package containing an object wrapped in overlap film is typically manufactured in the following mechanical manufacturing process: For example, a long piece of overlap film is formed into a tube that encloses the object to be wrapped, and both ends along the MD direction (longitudinal direction) are heat-sealed. The long piece of overlap film formed into a tube that encloses the object to be wrapped is then heat-sealed in the TD direction on both the front and rear sides of the object to obtain the package by heating the overlap film, which is sealed on three sides with the object inside, to cause it to shrink. [Examples]

[0055] The present invention will be described in more detail below using examples. The present invention is not limited to the scope of these examples. Hereinafter, "parts" and "%" refer to mass unless otherwise specified.

[0056] (Preparation of various compositions) As the anchor coat layer forming composition to be used in the comparative example, an oil-based anchor coat varnish, Preparation Example - Oil-based AC (for comparative example), as shown in Table 1 below, was prepared. As inks, we prepared oil-based color inks as shown in Table 2 below, from Preparation Example-Oil-Based Color 1 to Preparation Example-Oil-Based Color 4. As inks, we prepared oil-based white inks as shown in Table 3 below, from Preparation Example-Oil-Based White 1 to Preparation Example-Oil-Based White 4. As inks, we prepared the water-based color inks shown in Table 4 below, from Preparation Example-Water-based Color 1 to Preparation Example-Water-based Color 4. As inks, we prepared water-based white inks as shown in Table 5 below, from Preparation Example-Water-based White 1 to Preparation Example-Water-based White 4.

[0057] [Table 1]

[0058] The following ingredients were used in the table. Chlorinated polypropylene resin: Nippon Paper Industries Co., Ltd. "Supercron 360T, 60% solids content" Silica: "Silysia 436" manufactured by Fuji Silysia Chemical Co., Ltd.

[0059] <Preparation example - oil-based AC> A mixture of 30.3 parts chlorinated polypropylene resin (60% solution), 37.7 parts methylcyclohexane, 19.0 parts n-propyl acetate, 11.5 parts n-propyl alcohol, and 1.5 parts silica was stirred to prepare a sample of oily AC (for comparative example).

[0060] [Table 2]

[0061] The following raw materials were used in the table. Carbon Black: Orion Engineered Carbons "Special Black 250 Powder" Chlorinated polypropylene resin: Nippon Paper Industries Co., Ltd. "Supercron 360T, 60% solids content" Nitrocellulose resin: NOBEL Corporation's "NITROCELLULOSE DHX3-5" Polyamide resin: Commercially available 100% solid polyamide resin Ketone formaldehyde resin: Commercially available 100% solid ketone formaldehyde resin Silica: "Silysia 436" manufactured by Fuji Silysia Chemical Co., Ltd.

[0062] <Preparation Example - Oil-based Color 1> A mixture of 15.0 parts carbon black, 16.6 parts chlorinated polypropylene resin (60% solution), 41.3 parts n-propyl alcohol, and 26.1 parts n-propyl acetate was kneaded, and 1.0 part silica was added to prepare oil-based color 1.

[0063] <Preparation Example - Oil-based Color 2> 15.0 parts carbon black, 8.3 parts chlorinated polypropylene resin (60% solution), 4.0 parts solids of nitrate resin, 3.1 parts solids of polyamide resin, 1.2 parts solids of ketone formaldehyde resin, 41.3 parts n-propyl alcohol, and 26.1 parts n-propyl acetate were mixed and kneaded, and 1.0 part silica was added to prepare Example 2 - Oil-based Color.

[0064] <Preparation Example - Oil-based Color 3> 15.0 parts carbon black, 6.1 parts chlorinated polypropylene resin (60% solution), 6.2 parts solids of nitrate resin, 3.1 parts solids of polyamide resin, 1.2 parts solids of ketone formaldehyde resin, 41.3 parts n-propyl alcohol, and 26.1 parts n-propyl acetate were mixed and kneaded, and 1.0 part silica was added to prepare Example - Oily Color 3.

[0065] <Preparation Example - Oil-based Color 4> A mixture of 15.0 parts carbon black, 8.1 parts nitrate resin solids, 6.1 parts polyamide resin solids, 2.4 parts ketone formaldehyde resin solids, 41.3 parts n-propyl alcohol, and 26.1 parts n-propyl acetate was kneaded, and 1.0 part silica was added to prepare Example - Oil-based Color 4.

[0066] [Table 3]

[0067] The following raw materials were used in the table. Titanium dioxide: Teika Corporation's "TITANIX JR-808" Chlorinated polypropylene resin: Nippon Paper Industries Co., Ltd. "Supercron 360T, 60% solids content" Polyamide resin: Commercially available 100% solid polyamide resin Ketone formaldehyde resin: Commercially available 100% solid ketone formaldehyde resin Nitrocellulose resin: NOBEL Corporation's "NITROCELLULOSE DHX3-5" Silica: "Silysia 436" manufactured by Fuji Silysia Chemical Co., Ltd. Paraffin wax: "Accumelt 8756A" manufactured by THE INTERNATIONAL GR.

[0068] <Preparation Example - Oil-based White 1> 51.8 parts titanium dioxide, 12.2 parts chlorinated polypropylene resin (60% solution), 21.2 parts n-propyl alcohol, 5.8 parts methylcyclohexane, and 5.0 parts n-propyl acetate were mixed and kneaded, and 2.5 parts silica and 1.5 parts paraffin wax were added to prepare Example - Oily White 1.

[0069] <Preparation Example - Oil-based White 2> 51.8 parts titanium dioxide, 6.1 parts chlorinated polypropylene resin (60% solution), 3.4 parts solids of polyamide resin, 1.7 parts solids of ketone formaldehyde resin, 1.0 part solids of nitrated cotton resin, 21.2 parts n-propyl alcohol, 5.8 parts methylcyclohexane, and 5.0 parts n-propyl acetate were mixed and kneaded, and 2.5 parts silica and 1.5 parts paraffin wax were added to prepare Example - Oily White 2.

[0070] <Preparation Example - Oil-based White 3> 51.8 parts titanium dioxide, 4.7 parts chlorinated polypropylene resin (60% solution), 4.8 parts solids of polyamide resin, 1.7 parts solids of ketone formaldehyde resin, 1.0 part solids of nitrate resin, 21.2 parts n-propyl alcohol, 5.8 parts methylcyclohexane, and 5.0 parts n-propyl acetate were mixed and kneaded, and 2.5 parts silica and 1.5 parts paraffin wax were added to prepare Example - Oily White 3.

[0071] <Preparation Example - Oil-based White 4> 51.8 parts titanium dioxide, 6.9 parts solids of polyamide resin, 3.3 parts solids of ketone formaldehyde resin, 2.0 parts solids of nitrate resin, 21.2 parts n-propyl alcohol, 5.8 parts methylcyclohexane, and 5.0 parts n-propyl acetate were mixed and kneaded, and 2.5 parts silica and 1.5 parts paraffin wax were added to prepare Example - Oily White 4.

[0072] [Table 4]

[0073] The following raw materials were used in the table. Carbon Black: CABOT's "REGAL 330R Carbon Black" Chlorinated polypropylene resin: Commercially available aqueous chlorinated polypropylene resin solution with 30% solids content. Water-based acrylic resin solution: BASF "JONCRYL PDX-7741" Polyethylene wax: "Chemipearl W-400" manufactured by Mitsui Chemicals, Inc.

[0074] <Preparation Example - Water-based Color 1> 20.0 parts carbon black, 48.8 parts chlorinated polypropylene resin (30% solution), 6.3 parts n-propyl alcohol, and 23.0 parts water were mixed and kneaded, and 1.9 parts polyethylene wax was added to prepare Example Aqueous Color 1.

[0075] <Preparation Example - Water-based Color 2> A mixture of 20.0 parts carbon black, 24.5 parts chlorinated polypropylene resin (30% solution), 24.3 parts of a commercially available aqueous acrylic resin solution with a solid content of 30% including water, 6.3 parts n-propyl alcohol, and 23.0 parts water was prepared and kneaded. 1.9 parts polyethylene wax was then added to prepare Example Aqueous Color 2.

[0076] <Preparation Example - Water-based Color 3> Mixing 20.0 parts carbon black, 24.3 parts chlorinated polypropylene resin (30% solution), 24.5 parts of a commercially available aqueous acrylic resin solution with a solid content of 30% including water, 6.3 parts n-propyl alcohol, and 23.0 parts water, then kneading the mixture and adding 1.9 parts polyethylene wax to prepare the aqueous color 3.

[0077] <Preparation Example - Water-based Color 4> Mixing 20.0 parts of carbon black, 48.8 parts of a commercially available aqueous acrylic resin solution with a solid content of 30% including water, 6.3 parts of n-propyl alcohol, and 23.0 parts of water, then kneading the mixture and adding 1.9 parts of polyethylene wax to prepare Example Aqueous Color 4.

[0078] [Table 5]

[0079] The following raw materials were used in the table. Titanium dioxide: Teika Corporation's "TITANIX JR-808" Chlorinated polypropylene resin: Commercially available aqueous chlorinated polypropylene resin solution with 30% solids content. Water-based acrylic resin solution: BASF "JONCRYL PDX-7741" Polyethylene wax: "Chemipearl W-400" manufactured by Mitsui Chemicals, Inc.

[0080] <Preparation example-Aqueous white 1> 28.0 parts titanium dioxide, 57.6 parts chlorinated polypropylene resin (30% solution), 4.2 parts n-propyl alcohol, and 7.2 parts water were mixed and kneaded, and 3.0 parts polyethylene wax was added to prepare Example Aqueous White 1.

[0081] <Preparation example-Aqueous white 2> 28.0 parts titanium dioxide, 28.9 parts chlorinated polypropylene resin (30% solution), 28.7 parts of a commercially available aqueous acrylic resin solution with a solid content of 30% including water, 4.2 parts n-propyl alcohol, and 7.2 parts water were mixed and kneaded, and 3.0 parts polyethylene wax was added to prepare Example Aqueous White 2.

[0082] <Preparation example-Aqueous white 3> 28.0 parts titanium dioxide, 28.7 parts chlorinated polypropylene resin (30% solution), 28.9 parts of a commercially available aqueous acrylic resin solution with a solid content of 30% including water, 4.2 parts n-propyl alcohol, and 7.2 parts water were mixed and kneaded, and 3.0 parts polyethylene wax was added to prepare Example Aqueous White 3.

[0083] <Preparation example-Aqueous white 4> 28.0 parts titanium dioxide, 57.6 parts of a commercially available aqueous acrylic resin solution with a solid content of 30% including water, 4.2 parts n-propyl alcohol, and 7.2 parts water were mixed and kneaded, and 3.0 parts polyethylene wax was added to prepare Example Aqueous White 4.

[0084] (Printing method) The inks described in the preparation examples (oil-based color ink, oil-based white ink, water-based color ink, and water-based white ink) were each prepared in a Zahn cup #4 (manufactured by Rigosha) for 10 seconds (25°C) using a mixed organic solvent of propyl n-acetate / n-propyl alcohol = 50 / 50. Using a SOLOFLEX CI-type 6-color flexographic printing press manufactured by Windmiller Corporation, various inks were printed onto a polyolefin film substrate to obtain laminates (printed ink laminates) with the configurations shown in Tables 6 to 8 below. The ink was printed sequentially on the polyolefin film substrate, with a color ink layer followed by a white ink layer. As a comparative example, a laminate was also prepared in which an anchor coat layer was placed between the polyolefin film substrate and the ink layer. In this case, the oil-based anchor coat varnish described in the preparation example was prepared with methylcyclohexane in a Zaan cup #4 (manufactured by Rigosha) for 10 seconds (25°C). The ink preparation is as described above. Using a Windmiller SOLOFLEX CI-type 6-color flexographic printing press, an anchor coat layer and various inks were printed onto a polyolefin film substrate. The anchor coat layer, color ink layer, and white ink layer were printed sequentially on the polyolefin film substrate in that order.

[0085] The polyolefin film substrates used in each of the examples and comparative examples described in Tables 6 to 8 are as follows: The substrates used in Examples 1-6 and Comparative Examples 1-4 were heat-shrinkable polyolefin substrates, specifically biaxially oriented polypropylene films (13.5 μm thick) manufactured by Kojin Film & Chemicals Co., Ltd. Furthermore, the substrates used in Examples 7 and 8 were non-shrinkable polyolefin CPP substrates, specifically unoriented polypropylene film (30 μm thick) manufactured by Futamura Chemical Co., Ltd. Furthermore, the substrates used in Examples 9 and 10 were non-shrinkable polyolefin LLDPE substrates, specifically linear low-density polyethylene film (60 μm thick) manufactured by RM Tohcello Co., Ltd.

[0086] The laminates (printed ink laminates) prepared in Tables 6 to 8 were subjected to the evaluations described below.

[0087] (Evaluation of laminates) [Printability (Ink Transferability)] The transferability of various colored and white inks onto the polyolefin film, or onto the anchor coat layer in the case of the comparative example, when the ink was printed using the method described in the (Printing Method) section above, was visually evaluated. -Evaluation Criteria- 4. No ink transfer defects were observed at all. 3. Poor ink transfer is rarely observed. 2. Slight ink transfer defects can be observed. 1. Significant ink transfer defects are observed.

[0088] [Pre-shrinkage adhesion] After printing the ink using the method described in the (Printing Method) section above, cellophane tape (manufactured by Nichiban Co., Ltd.) was applied to the printed surface after the ink layer was printed. The tape was then quickly peeled off, and the condition of the printed surface was visually evaluated. Note that pre-shrinkage adhesion refers to the adhesion of a laminate (printed material) that has not been heated or subjected to thermal shrinkage after printing. -Evaluation Criteria- 4. The printed coating does not peel off the film at all. 3. Less than 30% of the printed coating area is peeled off the film. 2. The area ratio of the printed film is 30% or more and less than 50% that peels off from the film. 1. More than 70% of the printed surface area is peeled off from the film.

[0089] [Pre-shrinkage scratch resistance] After printing the ink using the method described in the (Printing Method) section above, the surface of the ink layer of the resulting laminate (printed material) was rubbed back and forth 20 times with a fingernail, and the degree to which the coating on the printed surface was removed was visually evaluated. -Evaluation Criteria- 3. The printed coating does not peel off the film substrate at all. 2. Less than 30% of the printed coating area is peeled off from the film substrate. 1. More than 70% of the printed surface area is peeled off from the film substrate.

[0090] [Pre-shrinkage kneading resistance] After printing the ink using the method described in the (Printing Method) section above, the surfaces of the ink layer of the resulting laminate (printed material) were rubbed back and forth five times, and the degree to which the coating on the printed surface was removed was visually evaluated. -Evaluation Criteria- 3. The printed coating does not peel off the film substrate at all. 2. Less than 30% of the printed coating area is peeled off from the film substrate. 1. More than 70% of the printed surface area is peeled off from the film substrate.

[0091] [Post-shrinkage adhesion] After printing the ink using the method described in the (Printing Method) section above, the resulting laminate (printed material) was shrunk in a constant temperature bath at 120°C for 30 seconds. Next, cellophane tape (manufactured by Nichiban Co., Ltd.) was applied to the printed surface, then the tape was quickly peeled off, and the condition of the printed surface was visually evaluated. Post-shrinkage adhesion refers to the evaluation of adhesion in a laminate (printed material) that has been heat-shrinked after printing. Therefore, this evaluation is performed only in cases where heat-shrinkable polyolefin film is used as the substrate, and is not performed on non-shrinkable polyolefin film because shrinkage due to heat heating is not anticipated. -Evaluation Criteria- 4. The printed coating does not peel off the film at all. 3. Less than 30% of the printed coating area is peeled off the film. 2. The area ratio of the printed film is 30% or more and less than 50% that peels off from the film. 1. More than 70% of the printed surface area is peeled off from the film.

[0092] [Blocking resistance] After printing the ink using the method described in the (Printing Method) section above, the ink layer surface of the resulting laminate (printed material) was placed against the film substrate, and the test was conducted using a blocking tester under the conditions of pressure: 0.5 MPa, temperature: 40°C, and humidity: 80% for one day. After the test, the peelability and condition of the surface were evaluated. -Evaluation Criteria- 4. When peeling the printed surfaces together, they peeled off without resistance, and there were no particular problems with the surface. 3. When peeling the printed surfaces apart, there is some resistance, and you can see that the surfaces are slightly stuck together. 2. When peeling the printed surfaces together, there is resistance, but the ink layer surface does not peel off. 1. When peeling the printed surfaces apart, there is considerable resistance, and the ink layer is peeling off.

[0093] [Heat resistance] After printing the ink using the method described in the (Printing Method) section above, the ink layer surface of the resulting laminate (printed material) after ink layer printing is placed against a polystyrene sheet representing a container to which the printed surface will be stored, and then pressed together with a heat sealing bar at a pressure of 0.1 MPa for 1 second to check the degree to which the coating on the printed surface has been removed. Test temperature: 120℃ -Evaluation Criteria- 4. The printed coating is not removed from the polystyrene sheet at all. 3. The printed coating covers less than 30% of the surface area of ​​the polystyrene sheet. 2. The printed coating covers less than 50% of the surface area of ​​the polystyrene sheet. 1. The printed coating covers 70% or more of the surface area of ​​the polystyrene sheet.

[0094] (Examples 1-10, Comparative Examples 1-2) The evaluation results for the laminates (printed materials) of the examples and comparative examples shown in Tables 6 to 8 below are shown in the same Tables 6 to 8.

[0095] [Table 6]

[0096] [Table 7]

[0097] [Table 8]

[0098] It has been found that laminates (printed materials) having an ink layer formed using the ink layer-forming composition of the present invention are laminates that ensure adhesion as a laminated film while also having good printability (ink transferability) in the areas where ink is applied in layers. Furthermore, in Tables 6 to 8, if the evaluation score is 2 or higher, the laminate can be used in practical applications. Furthermore, a laminate (printed material) having an ink layer formed using the ink layer-forming composition of the present invention may not only have excellent adhesion but also be a laminate with excellent printability when ink is applied in multiple layers (also known as ink overprinting).

Claims

1. A composition for forming an ink layer for direct coating of polyolefin film, It contains a binder resin, a colorant, and a solvent. The aforementioned binder resin is an ink layer forming composition that contains a chlorinated polyolefin resin as the main component among the binder resin components.

2. The ink layer forming composition according to claim 1, wherein the binder resin further contains at least one of the following resins: nitrated cotton resin, polyamide resin, ketone formaldehyde resin, and acrylic resin.

3. The ink layer forming composition according to claim 1 or 2, wherein, when the ink layer forming composition is an oil-based ink composition, the solvent is an organic solvent containing at least one of an aliphatic hydrocarbon solvent, an ester solvent, an alcohol solvent, and a glycol ether solvent.

4. The ink layer forming composition according to claim 1 or 2, wherein the solvent contains water when the ink layer forming composition is an aqueous ink composition.

5. Furthermore, the ink layer forming composition according to claim 1 or 2 further contains at least one of wax and silica.

6. A laminate comprising a polyolefin film and an ink layer laminated adjacent to each other, A laminate in which the ink layer is a layer formed using the ink layer forming composition described in claim 1 or 2.

7. The laminate according to claim 6, wherein the polyolefin film is a heat-shrinkable film.

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